We described how you can reopen the last closed tab in Safari for macOS by simply pressing Command-Z (⌘-Z). Turns out you can reopen the last closed tab on mobile Safari as well.
On mobile Safari bottom toolbar, tap on the Tabs button. On the Tabs screen that pops up, locate the Add (+) button on the bottom toolbar.
Tap and hold on the Add icon to bring up the “Recently Closed Tabs” listing. Simply tap on the list item to bring back the website you recently visited.